Thomas a



UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF MENLO PARK, NElV JERSEY, ASSIGNOR TO THE EDISON ELECTRIC LIGHT COMPANY, OF NEW YORK, N. Y.

MANUFACTURE OF INCANDESCENT LAMPS.

SPECIFICATION forming part of Letters Patent No. 430,932, dated June 24, 1890.

Application filed October 20, 1882. Serial No. 74,780. (No specimens.)

To aZZ whom it may concern.-

Be it known that I, THOMAS A. EDISON, of Menlo Park, in the county of Middlesex and State of New Jersey, have invented a new and usc'fullmprovement in the Manufacture of Incandescing Electric Lamps, (Case No. 492,) of which the following is a specification.

The object I have in view is to exhaust the inclosingglobes of incandescing electric lamps to an almost complete vacuum in a simple and efficient manner, which will not require the use of vacuum-pumps or other complicated apparatus.

The lamp when ready for the exhausting process consists of a glass stem supporting the carbon filament and having the leadingin wires sealed within it, such glass stem being sealed within an outer inclosing-globe, from the top of which extends a long glass tube or stem.

In carrying out my invention I fill the globe through the tube or stem with a liquid, preferably one the tension of whose vapor is low even at high temperatures and at the freezing point is practically nothing, so that such vapor condenses readily and completely at the freezing-point, oil of turpentine being exceedingly suitable for the purpose. I then invert the lamp and immerse the end of the stem in a bath of the same liquid. I then heat the liquid to form turpentine or other vapor, (according to the liquid used,) and continue this heating until the tension of the gas is suflicient to drive all the oil out into the stem. The heating may be accomplished either by heating the globe externally or by passing an electric current through the incandescin g filament. The stem is then sealed ofi at a point above the liquid. An atmosphere of turpentine or equivalent vapor thus remains in the lamp and the remaining portion of the stem. I now again heat the bulb, at the same time immersing the end of the stem or exhaust-tube in a powerful freezingmixture. The heating of the vapor drives out such vapor from the globe and the freezing-mixture causes said vapor to be con-. densed in the exhaust-tube. This tube is again sealed 01f, this time close to the lamp globe, so that the globe now contains a containing charcoal or other absorbent material to take up any vapor which may fail to condense in the tube, this bulb being atterward sealed off from the globe.

I am aware that patent to Maxim, No. 230,953, dated August 10, 1880, describes a process consisting in displacing the air in a lamp-globe by liquid gasoline and then expelling such liquid in such manner as to leave in the globe an atmosphere of hydrocarbon vapor.

What I claim is- 1. The process of exhausting the inclosingglobe of an incandescing electric lamp, consisting in filling said globe with a liquid, in verting the globe, heating said globe, and expelling all of said liquid by the tension of the vapor produced by said heating, and again heating said globe externally to expel said vapor, the carbon filament of the lamp being heated to incandescence by an electric current during the latter external heating, substantially as set forth.

2. The process of exhausting the inclosingglobe of an incandescing electric lamp, consisting in filling said globe with a liquid the tension of whose vapor is low at high temperatures, inverting the globe, heating said globe, and expelling all of said liquid by its vapor-tension, and again heating said globe to expel the vapor, at the same time lowering the temperature of the exhaust-tube to condense said vapor, substantially as set forth.

3. The process of exhausting the inclosingglobe of an incandescing electric lamp, consisting in filling said globe with a liquid, inverting the globe, heating said globe, and expelling all of said liquid by its vapor-tension, sealing off the exhaust-tube at some distance from its connection with the lamp, heating the globe, while at the sametime the temper ature of-ithe remain-ingportion of the exhaust tube is greatly reduced, thereby expelling the vapor from the globe and condensing itin 5 the tube, and finally sealing off the tube close to the globe, substantially asset forth;

4.1 The process of exhaustingthe inclosinga L globe of an inoandescingeleetric lamp,"-con'-- '1 sisting in filling said globe with oil of tur- I0 pentine, inverting the globe,i heati ng.'saidthis l ithday of-Oot0ber,'1882. V 4 1 THUS? Af- EDISON".

lVitnesses:

H. W. SEELY,

3 RIOHDrN; DYER; 

